1. Field of the Invention
The present invention relates to a vehicle-use power generation control device for controlling an output voltage of a generator mounted on a vehicle such as a passenger car or a truck.
2. Description of Related Art
There is known a vehicle-use charging system including an external control device and a power generation control device between which two-way communication can be performed. In this system, the external control device transmits a power generation control command to the power generation control device depending on a running state of a vehicle engine and a charge state of a vehicle battery detected by use of sensors in order to optimally perform power generation control in accordance with a vehicle running state, and on the other hand, the power generation control device transmits a power generation state signal to the external control device to enable performing engine control in accordance with a power generation state. For example, refer to Japanese Patent Application Laid-open No. 2003-88191.
In such a system, since the charge/discharge characteristic of the battery varies depending on its temperature, it is desirable that the external control device directs a target power generation voltage determined depending on the temperature of the battery detected by a battery temperature sensor to the power generation control device. However, in this case, the manufacturing cost of the system increases because in general battery temperature sensors are expensive. In addition, since the battery temperature sensor and the external control device have to be connected to each other by a harness, the wiring structure of the system becomes complicated.